The invention relates to a method for preventing or treating common cold or treating pain by administering a new agent comprising a) at least one chitin oligosaccharide; b) at least one chitosan oligosaccharide; c) at least one partially deacetylated chitin oligosaccharide, wherein some, but not all, of the N-acetyl glucosamine or 2-acetamido-2-deoxy-D-glucose subunits are de-acetylated; d) a mixture of at least one chitin oligosaccharide and at least one chitosan oligosaccharide; e) a mixture of at least one chitin oligosaccharide and at least one partially deacetylated chitin oligosaccharide; or f) a mixture of at least one chitosan oligosaccharide and at least one partially deacetylated chitin oligosaccharide to a subject in need of common cold prevention or treatment or pain treatment. The new agent may further comprise N-acetyl glucosamine and/or glucosamine. The new agent may induce analgesia by absorbing, binding, or otherwise inhibiting bradykinin and ions at the nerve endings as its mechanism. This invention also relates to an oral method of delivery. The new agent is useful in the prevention of the common cold (non-allergic rhinitis, viral upper respiratory tract infection, viral URI, etc) and in reducing the duration and severity of the symptoms of such an infection should this occur.
The common cold, one of mankind""s most frequent disease afflictions (also called non-allergic rhinitis, viral upper respiratory tract infection, viral URI) is a contagious infectious disease that, while usually self-limiting and non-fatal, has long been a source of limitless suffering with huge expenditures of time and money, as well as being a leading cause of doctor visits. Very few humans escape infection each year and most will suffer multiple infections. It is estimated that most adults will suffer 2-5 colds per year while infants and pre-school children may have 4-8 such infections each year (1). In the course of a year, individuals in the U.S. suffer from over one billion colds which are a leading cause of school and job absenteeism as well as doctor visits. Broken down further, children have more colds than adults probably due to their relative lack of resistance to infection and to contact with other infected children in school and daycare centers. Women, particularly in the age range 20-30, have more colds than men due to their closer contact with children (2). The economic impact of the common cold can only be estimated. According to the National Center for Health Statistics, in 1995, 61 million cases of the common cold required medical attention. There were 58 million bed days lost to the common cold, 24 million days of restricted activity, and 22 million lost school days (3). The exact dollar figure spent or lost can only be estimated but probably is in the tens of billions. (It should be noted that these figures are for the United States only).
Although rarely fatal in and of itself, the common cold may lead to more serious complications in the very young, the very old, and those that are immunocompromised. Such complications include bacterial suprainfection, pneumonia, bacterial sinusitis, and otitis media. In addition, the common cold is responsible for many exacerbations of asthma, a serious multi-billion dollar per year respiratory disease responsible for over 5,000 deaths per year, a figure that keeps rising (4,5,6).
Yet despite the prevalence, destructiveness, and costs of the disease, surprisingly little or no progress has been made toward effective cold treatment (7). Antibiotics, which are prescribed with disturbing frequency by practitioners and demanded by patients who want xe2x80x9csomething donexe2x80x9d, are ineffective both theoretically and in practice since the common cold is caused by a virus, not a bacteria (see Detailed Description of the Invention for a discussion of the pathology of the common cold) (8, 9, 10). In fact, the misuse and over-prescription of antibiotics for the common cold has led to dangerous mutant resistant strains of micro-organisms such as MRSA (methacillin resistant staphylococcus aureus). Vitamin C, as proclaimed by two-time Nobel Prize winner Dr. Linus Pauling, has also been reputed to both prevent colds and decrease the symptoms should a cold occur, when given in so-called xe2x80x9cmega dosesxe2x80x9d ie greater than 5-10 grams per day (RDA=65-130 mg per day). However, numerous studies since Dr. Pauling""s work have failed to duplicate his results, and the role of vitamin C, if any, is still open to debate (11, 12, 13, 14, 15). Over-the-counter cold prescriptions invariably act to suppress symptoms locally through actions against such things as histamine (the antihistamine group of drugs ie Benadryl) or through various actions on the autonomic nervous system (such as ephedrine-a sympathomimetric amine. It should be noted that these drugs have side effects, some of which can be serious. Other experimental drugs such as BIRR 4 (also called tremacara) must be applied directly to the nose before being exposed to the virus, which does little good for the average individual who has no idea when or where he will come in contact with the cold virus. However, experiments involving tremacara have proven clinically the theoretical efficacy of blocking the rhinovirus/ICAM-1 receptor sites for reducing the severity of rhinovirus cold infections. A variety of alternative and folk remedies (zinc, ecchinacea, etc) have also been used over the years with variable and largely unreproducable results (16,17). Thus, there is a need for an agent effective in preventing and/or treating common cold. The present invention concerns such an agent and a method of preventing and/or treating common cold.
Pain and the suffering it causes is one of the oldest afflictions known to man/ The relief of such pain and suffering has long been one of the most solemn duties of the health professional. Between 75-100 million Americans suffer from chronic pain; osteoarthritis alone affects over 25 million Americans and over 40 million experience chronic recurring headaches. Upwards of $4,000,000,000 are spent on pain medication alone (not to mention physician fees, lost work time, hospitalization, etc) and it is estimated that chronic pain may play a factor in up to 50% of suicides. Yet despite the expense and trouble, 60-80% of people say that they are dissatisfied with their pain medication (28).
The International Association for the Study of Pain defines pain as xe2x80x9can unpleasant sensory or emotional experience arising from actual or potential tissue damage or described in terms of such damagexe2x80x9d.
Acute pain is one dimensional and is always a sign or symptom of underlying pathology. Chronic pain (arising from a chronic condition, an injury that lasts longer than expected, or for which there is no known cause i.e. fibromyalgia) is considered to be without purpose and may be properly considered a disease.
Analgesics have classically been considered into three major groups:
1) central acting (opioids, tramadol);
2) peripheral acting (non-steroidal anti-inflammatory drugs also called NSAIDS as well as acetaminophen commonly called Tylenol); and
3) local (steroid injections, etc).
The opioids variably block and stimulate certain areas of the brain involved in pain and its perception. However, all narcotics can and do cause:
increasing tolerance (more and more of the drug is required as time goes on to achieve the same analgesic effect);
nausea and vomiting;
other gastrointestinal effects such as abdominal pain, constipation, and diarrhea;
addiction, with all of its social, legal, and financial implications as well as its toll on health;
overdose; and
sudden death (idiosyncratic reaction).
The peripheral acting agents which includes NSAIDS such as aspirin and other salicylates, ibuprofen, indomethacin, etc work by inhibiting the cyclooxygenase (COX) enzyme system in inflammatory cells thereby inhibiting prostaglandins and thus are of limited value in painful conditions where inflammation is not a prominent feature of the disease (such as osteoarthritis). Side effects of the NSADS include:
gastrointestinal symptoms such as heartburn, gastritis, ulcers, bleeding and hemorrhage compounded by
a prolonged bleeding time and platelet dysfunction;
kidney problems such as fluid and electrolyte imbalance, renal papillary necrosis, etc.; and
cardiovascular disorders such as high or low blood pressure, interference with other heart medications, etc.
The use of NSAIDS results in about 20,000 deaths and about 200,000 hospitalizations per year in the United States (28).
Acetaminophen (Tylenol) was developed in part to diminish these rather disturbing morbidity and mortality statistics. The exact mechanism of action of acetaminophen is not known, but it is believed that it may elevate the pain threshold. However, can and does cause liver damage and death when used in excess, especially in children.
Although considerable advances in the understanding of pain have been made, our understanding of the pathophysiology of chronic pain is incomplete (31). The disagreeably unpleasant sensation of pain is the result of an extremely complex series of events which are integrated at virtually all levels of the nervous system from the periphery via the dorsal horns of the spinal cord to the cerebrum and perhaps deeper structures (29).
Pain is frequently pathophysiologically classified into two groups:
1) nociceptive pain which results from stimulation of the nerve endings; and
2) neuropathic pain which results from actual damage to the nerves.
Nociceptive pain is further classified into:
1) visceral painxe2x80x94described as xe2x80x9cgnawingxe2x80x9d or xe2x80x9cthrobbingxe2x80x9d; and
2) somatic painxe2x80x94described as xe2x80x9cdullxe2x80x9d or xe2x80x9cachingxe2x80x9d.
Neuropathic pain is usually described as xe2x80x9csharpxe2x80x9d, xe2x80x9cburningxe2x80x9d or xe2x80x9cshootingxe2x80x9d.
Nociceptors can be defined as sensory receptors that are activated by noxious stimuli that damage or threaten the body""s integrity. Nociceptors belong to the slowly conducting afferent A delta and C fibers and may be further classified according to their responses to mechanical, chemical and thermal stimuli (30). They may be found in the skin, deep tissues and viscera, and as free nerve endings. Stimulation and pain is accomplished via thermal mechanisms and ionic changes and are mediated through a variety of substances such as prostaglandin E2 (which the COX inhibition of NSAIDS effects), free radicals, and kinins such as bradykinin.
Bradykinin is formed in the blood from precursor kininogens and is a nonapeptide with the following amino acid sequence:
Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg
It has a molecular weight of 1418.5 and is found in the plasma, the blood, in endothelium, and in the damaged tissue itself. It is released from kininogens by the action of kallikrein enzymes (32) and evokes a variety of biological responses besides the induction of pain including smooth muscle contraction and relaxation as well as inflammation.
Bradykinin exerts its pain inducing effects via binding to receptor sites on the sensory neurons. Bradykinin receptors are cell-surface G-protein coupled receptors and are of two types called B1 and B2, although it appears certain that there are more subsets in each category.
B1 receptors appear to be important modulators of pain and inflammation but their overall role is not clear at this point; they appear to be more involved with chronic inflammatory responses and persistent hyperalgesia after injury (33).
B2 receptors are the more important in mediating pain as well as more classic events involving inflammation such as edema, etc. Evidence suggests that bradykinin is bound partially by the helical bundle of the receptor with the amino terminus actually protruding from the extracellular side of the helical bundle of the receptor (34).
Peptide bradykinin antagonists have been studied, but their use is limited due to poor oral absorption and very short duration of action.
Non-peptide bradykinin antagonists, until now, have come from plants and include flavonoids and terpenes as well as certain synthetics such as pregnane glycoside compounds. However, these non-peptide bradykinin antagonists suffer disadvantages, e.g. these antagonists are relatively difficult to obtain. As a result, there is a need for other non-peptide bradykinin antagonists. The agent of the present invention fulfills such a need.
One aspect of the present invention concerns an agent comprising
a) at least one chitin oligosaccharide;
b) at least one chitosan oligosaccharide;
c) at least one partially deacetylated chitin oligosaccharide, wherein some, but not all, of the N-acetyl glucosamine or 2-acetamido-2-deoxy-D-glucose subunits are de-acetylated;
d) a mixture of at least one chitin oligosaccharide and at least one chitosan oligosaccharide;
e) a mixture of at least one chitin oligosaccharide and at least one partially deacetylated chitin oligosaccharide; or
f) a mixture of at least one chitosan oligosaccharide and at least one partially deacetylated chitin oligosaccharide,
to function as a non-peptide, bradykinin antagonist. Preferably, the chitin oligosaccharide and/or chitosan oligosaccharide is water soluble. In addition to component a) to f), the agent of the present invention may further comprise N-acetyl glucosamine and/or glucosamine. The agent of the present invention is also effective in preventing and/or treating common cold. The agent can be absorbed systemically after being administered orally.
The agent of the present invention is a novel analgesic and is:
effective against mild, moderate and severe pain;
effective against a variety of types of pain (pain associated with cancer, fibromyalgia, toothache, headache, etc);
has no known serious adverse side effects;
is non-addicting;
is safe for children, adults, and pregnant females; and
is orally administered.
To understand the mechanism of action of the agent (i.e. the agent comprising at least one chitin oligosaccharide, at least one chitosan oligosaccharide, or a mixture of at least one chitin oligosaccharide and at least one chitosan oligosaccharide) of the present invention in the prevention and therapy of the common cold, an explanation of the pathobiology of the disease is necessary.
The etiologic agent of the common cold is a virus, a micro-structure characterized by a nucleic acid (either DNA or RNA) enclosed in a protein capsid. Although a number of types of virus (adenovirus, coronavirus, etc) have been shown to be capable of causing the classic symptoms of cold, the most prevalent (40-70% depending upon the study) organism is the rhinovirus. The rhinovirus is a 30 nm RNA virus with over 100 serotypes (some studies say over 200) that belongs to the Picornaviridae family (so does polio virus) and replicates only in primates. The single-stranded positive genome acts as a template for both RNA synthesis and viral replication. The rhinovirus is made of 60 geometric arrangements called isocahedrons and there are four viral proteins named VP1, VP2, VP3, VP4; the whole conformation is known as a pentamer which is formed by the chain of carbon atoms composing each viral particle. The isocahedrons demonstrate deep xe2x80x9ccanyonsxe2x80x9d or xe2x80x9cvalleysxe2x80x9d in their surface and thus present at least 60 different sites to bind to intercellular adhesion molecule one (ICAM-1). Thus, the viral-receptor attachment site lies in a cavity that is inaccessible to the host""s antibodies. In addition to the above and to the large number of different serotypes of rhinovirus, there is no common antigen found among rhinovirus, thus inhibiting development of an effective cold vaccine.
Rhinoviruses are transmitted mainly via direct or indirect contact with infected secretions and invade their host by binding to the ICAM-1 receptor on the nasal epithelium.
ICAM-1 (intercellular adhesion molecule one) is a single protein that normally functions by binding leukocytes in places and in regions of the body where required. It has been shown to shaped somewhat like and arm with 5 sections or domains. Near the xe2x80x9chandxe2x80x9d end of the molecule are 3 finger-like projections; this is where the rhinovirus attaches. The deep xe2x80x9ccanyonsxe2x80x9d and xe2x80x9cvalleysxe2x80x9d on the capsid of the rhinovirus fits onto these projections and thus the virus can gain entry into the cells with little or no detection by the immune system. It should be noted that each cell may contain thousands of these receptor sites on the cell membrane; thus, infection, viral replication, and clinical disease may be relatively simple and rapid.
Although the exact events in the pathobiology of human rhinovirus infection from exposure through clinical disease to recovery has not been completely elucidated, the sequence of events has been determined to be exposure to the virus via direct (coughing, sneezing, etc) or indirect (dirty hands, utensils, etc) contact. The virus then attaches to the receptor sites on the ICAM-1 molecule and due to the geography and stereo-chemistry of both the virus and receptor is relatively hidden from the immune system. The virus then gains entry into the nasal epithelial cells and begins replication. With viral replication, certain pro-inflammatory substances are produced, including bradykinin (and histamine) which are released and the well-known clinical symptoms are produced (watery itchy eyes, congestion, runny nose, cough sneezing, etc). The sequence of exposure, attachment to receptor site, cell entry, viral replication and the release of inflammatory substances with clinical illness offers the mechanism of common cold prevention and symptom reduction offered by the agent of the present invention.
Chitin is a naturally occurring biorenewable aminopolysaccharide consisting of N-acetyl glucosamine residues joined by xcex2-(1-4) glycosidic links. Chitosan is a de-acetylated chitin and is similarly joined by xcex2-(1-4) links. The basic chemical structures of some chitin and chitosan are shown in formulae 1 and 2, respectively. 
The molecular weight of chitin or chitosan may be over 1,000,000. (chitin and chitosan can be structurally arranged in what is known as the xe2x80x9cchair formxe2x80x9d, which also has xe2x80x9ccanyonsxe2x80x9d ). Chitin and chitosan are poorly absorbed orally (20-40%) and should be broken down into smaller (e.g. 2-12, 2-10 or 2-8 subunits) residues by processing in order to achieve complete absorption and thus systemic medical effect.
The term, xe2x80x9cchitin oligosaccharidexe2x80x9d, means an oligosaccharide having 2 to about 14, preferably 2 to about 12, more preferably 2 to about 10, even more preferably 2 to about 8, N-acetyl glucosamine subunits linked together. The chitin oligosaccharide can be selected from N-acetyl chitobiose, di-N-acetyl chitobiose, tri-N-acetyl chitotriose, tetra-N-acetyl chitotetraose, penta-N-acetyl chitopentaose, hexa-N-acetyl chitohexaose, hepta-N-acetyl chitoheptose, and octa-N-acetyl chitooctose. The term, xe2x80x9cchitosan oligosaccharidexe2x80x9d, means any chitin oligosaccharide having all of the N-acetyl groups removed.
The agent of the present invention can contain a combination of some or all of the chitin oligosaccharides selected from the group consisting of N-acetyl chitobiose, di-N-acetyl chitobiose, tri-N-acetyl chitotriose, tetra-N-acetyl chitotetraose, penta-N-acetyl chitopentaose, hexa-N-acetyl chitohexaose, hepta-N-acetyl chitoheptose, and octa-N-acetyl chitooctose in any proportion (e.g. in equal proportion; in a 2:1:1:1:1:1:1:1 proportion if 8 chitin oligosaccharides are present with one of the chitin oligosaccharides as the major chitin oligosaccharide component present in 2 of 9 parts by mole or by weight of the total amount of chitin oligosaccharides present in the agent; or in a 3:2:1:1:1 proportion if 5 chitin oligosaccharides are present with one of the chitin oligosaccharides as the major chitin oligosaccharide component present in 3 of 8 parts by mole or by weight and another of the chitin oligosaccharides as the second major chitin oligosaccharide component present in 2 of 8 parts by mole or by weight of the total amount of chitin oligosaccharides present in the agent).
The chitosan oligosaccharide can be selected from chitobiose, chitotriose, chitotetraose, chitopentaose, chitohexaose, chitoheptaose and chitooctose. The agent of the present invention can also contain a combination of some or all of chitobiose, chitotriose, chitotetraose, chitopentaose, chitohexaose, chitoheptaose and chitooctose in any proportion (e.g. in equal proportion; in a 2:1:1:1:1:1:1:1 proportion if 8 chitosan oligosaccharides are present with one of the chitosan oligosaccharides as the major chitosan oligosaccharide component present in 2 of 9 parts by mole or by weight of the total amount of chitosan oligosaccharides present in the agent; or in a 3:2:1:1:1 proportion if 5 chitosan oligosaccharides are present with one of the chitosan oligosaccharides as the major chitosan oligosaccharide component present in 3 of 8 parts by mole or by weight and another of the chitosan oligosaccharides as the second major chitosan oligosaccharide component present in 2 of 8 parts by mole or by weight of the total amount of chitosan oligosaccharides present in the agent).
In the agent of the present invention, at least one chitin oligosaccharide (i.e. chitin oligomer), preferably water soluble, may be present. The chitin oligosaccharide can contain more preferably 2 to about 10, even more preferably 2 to about 8, e.g. 2, 3, 4, 5 or 6, N-acetyl glucosamine or 2-acetamido-2-deoxy-D-glucose subunits. More preferred oligosaccharides of chitin include di-N-acetyl chitobiose, tri-N-acetyl chitotriose, tetra-N-acetyl chitotetraose, penta-N-acetyl chitopentaose, and hexa-N-acetyl chitohexaose. The agent of the present invention can contain a combination of different chitin oligosaccharides having different numbers (e.g. 2 to about 10, preferably 2 to about 8, more preferably 2 to about 6, and also more preferably about 4 to about 6 N-acetyl-glucosamine subunits) of N-acetyl-glucosamine subunits. For instance, the combination of different chitin oligosaccharides can be a mixture of different chitin oligosaccharides having 2, 3, 4, 5 and 6 N-acetyl-glucosamine subunits. Similarly, the combination of different chitin oligosaccharides contained in the agent of the present invention can be a mixture of different chitin oligosaccharides having 4, 5 and 6 N-acetyl-glucosamine subunits.
The agent of the present invention can contain at least one, preferably water soluble, partially deacetylated chitin oligosaccharide. The partially deacetylated chitin oligosaccharide can be any of the chitin oligosaccharides disclosed above with one or more, but not all, of the N-acetyl groups removed. The agent of the present invention can contain a combination of different partially deacetylated chitin oligosaccharides having different numbers (e.g. 2 to about 10, preferably 2 to about 8, more preferably 2 to about 6, and also more preferably about 4 to about 6 N-acetyl-glucosamine subunits) of N-acetyl-glucosamine subunits, wherein some of the N-acetyl groups are removed. For instance, the combination of different partially deacetylated chitin oligosaccharides contained in the agent of the present invention can be a mixture of different chitin oligosaccharides having 2, 3, 4, 5 and 6 N-acetyl-glucosamine subunits with some of the N-acetyl groups removed. Similarly, the combination of different partially deacetyled chitin oligosaccharides contained in the agent of the present invention can be a mixture of different chitin oligosaccharides having 4, 5 and 6 N-acetyl-glucosamine subunits with some of the N-acetyl groups removed.
The agent of the present invention can contain at least one, preferably water soluble, chitosan oligosaccharide (i.e. chitosan oligomer). The chitosan oligosaccharide can contain more preferably 2 to about 10, even more preferably 2 to about 7 or 8, e.g. 2, 3, 4, 5 or 6, glucosamine or 2-amino-2-deoxy-D-glucose subunits. More preferred oligosaccharides of chitosan include chitobiose, chitotriose, chitotetraose, chitopentaose, chitohexaose, and chitoheptaose. The agent of the present invention can contain a combination of different chitosan oligosaccharides having different numbers (e.g. 2 to about 10, preferably 2 to about 8, more preferably 2 to about 6, and also more preferably about 4 to about 6 glucosamine subunits) of glucosamine subunits. For instance, the combination of different chitosan oligosaccharides can be a mixture of different chitosan oligosaccharides having 2, 3, 4, 5 and 6 glucosamine subunits. Similarly, the combination of different chitosan oligosaccharides contained in the agent of the present invention can be a mixture of different chitosan oligosaccharides having 4, 5 and 6 glucosamine subunits.
The agent of the present invention, preferably, comprises a mixture of at least one chitin oligosaccharide and at least one chitosan oligosaccharide (CCOS). The at least one chitin oligosaccharide and at least one chitosan oligosaccharide can be the chitin oligosaccharides or combination of chitin oligosaccharides, and the chitosan oligosaccharides or combination of chitosan oligosaccharides disclosed above. Such a mixture preferably comprises di-N-acetyl chitobiose, tri-N-acetyl chitotriose, tetra-N -acetyl chitotetraose, penta-N-acetyl chitopentaose, hexa-N-acetyl chitohexaose, chitobiose, chitotriose, chitotetraose, chitopentaose, chitohexaose, and chitoheptaose.
Preferably, the chitin oligosaccharide, chitosan oligosaccharide and/or partially deacetylated chitin oligosaccharide ingredients of the agent of the present invention are water soluble. Being water soluble, these ingredients are well absorbed in the gastrointestinal tract and suitable for oral or intravenous administration. The ease of using water soluble chitin oligosaccharides, chitosan oligosaccharides and/or partially deacetylated chitin oligosaccharides imparts tremendous advantage over water insoluble polymers or oligosaccharides of chitin and/or chitosan.
In the method to prevent or treat common cold or to treat pain, the agent of the present invention can be administered at a dose of 0.01 mg/kg body weight to 10 g/kg body weight per day to a subject in need of the prevention or treatment of the common cold. The preferred dose is 0.1 mg/kg per day to 1 g/kg per day, and the more preferred dose is 1 mg/kg per day to 100 mg/kg per day. The agent, e.g. the mixture of chitin and chitosan oligosaccharides (CCOS), of the present invention can be administered orally (e.g. as a tablet, dietary supplement or food additive) or parenterally. Administration via the parenteral routes includes adminstering the agent dermally, by applying topically on a mucous membrane, by inhalation, intravenously, subcutaneously, intramuscularly, or intraperitoneally. The agent, e.g. the mixture of chitin and chitosan oligosaccharides (CCOS), of the present invention is effective in preventing or treating the common cold or treating pain in a subject, including animals and humans. The animal subjects can be non-human mammals.
The agent, e.g. the mixture of chitin and chitosan oligosaccharides (CCOS), of the present invention is effective if administered alone or in a pharmaceutical composition admixed with at least one pharmaceutically acceptable carrier. The pharmaceutical composition can be manufactured into a chewable tablet. The agent of the present invention, e.g. the CCOS mixture, can also be administered together with other agents, e.g. analgesics, antipyretics or nasal decongestants, commonly used in treating the common cold.
The chitin chitosan oligosaccharide mixture (CCOS) when taken orally in a dosage of about 100 mg TID, prevents the rhinovirus from binding to its receptor site on the ICAM-1 molecule found in the nasal epithelial cells. The virus is thus unable to gain entry into the nasal epithelium; disease and symptoms are prevented.
Should the viral load exceed the binding dosage capacity of the chitin chitosan oligosaccharide mixture or should the body be more susceptible for other reasons (concurrent illness, etc) infection, viral replication, and symptoms may ensue with the release of certain inflammatory substances and immune cytokines. Among the former is a substance called bradykinin. The most well-known clinical effect of bradykinin is the induction of pain, but as kinin (19) is involved with producing many of the symptoms associated with the common cold (20,21,22).
The agent of the present invention, e.g. the mixture of chitin chitosan oligosaccharides, blocks the action of bradykinin at its receptor sites, BR1 and Br2 (23), thus decreasing the severity and duration of symptoms.
Bradykinin is not the sole inflammatory kinin produced by rhinovirus infection. Among the other cytokines so produced is a substance called interferon gamma. Interferon gamma is a cytokine produced by T and B lymphocytes which activates, stimulates and otherwise affects a variety of immune functions such as natural killer cells (NK cells) activation, macrophage activation, stimulation of more T and B cells, etc. It has also been shown to down-regulate the expression of ICAM-1 in the human airway cells thus causing a reduction in viral titers (25). The said mixture of chitin chitosan oligosaccharides enhances the production of interferon gamma (26,27).and thus causes reduction of viral load and decreased substrate for infection.
Within the scope of the present invention, the agent, e.g. the mixture of chitin and chitosan oligosaccharides selected from di N-acetyl chitobiose, tri N-acetyl chitotriose, tetra N-acetyl chitotetraose, penta N-acetyl chitopentaose, hexa N-acetyl chitohexaose, and hepta N-acetyl chitoheptaose and chitosan oligosaccharides selected form chitobiose, chitotriose, chitotetraose, chitopentaose, chitohexaose, chitoheptaose, and chitooctose, of the present invention, can prevent infection by rhinovirus in the nasal musosa by blocking entry via receptor sites on the ICAM-1 molecule and the rhinovirus. Should overwhelming exposure occur and infection ensue, chitin chitosan oligosaccharides (CCOS) can decrease the length and severity of the symptoms by its actions on certain inflammatory kinins and cytokines; namely, CCOS blocks the receptor sites for bradykinin activity and enhances the production of the beneficial cytokine interferon gamma. CCOS may be given orally and has no side effects even when given in mega doses (ie greater than 50 grams per day) to human subjects.
Preferably, the chitin oligosaccharide, chitosan oligosaccharide, partially deacetylated chitin oligosaccharide ingredients of the agent of the present invention are water soluble. These water soluble chitin and chitosan oligosaccharides can be prepared from chitin and chitosan polymers.
The chitin oligosaccharides and the chitosan oligosaccharides can be obtained by chemically or biochemically treating chitin which is prepared from the shells of crustaceans such as crabs, lobsters or shrimp with optional acid hydrolysis, or by chemical synthesis with a method known.
The chitin oligosaccharide can be obtained by subjecting chitin to partial hydrolysis by an acid or an enzyme and if required fractionating or purifying the one with the desired degree of polymerization form the hydrosylate by a method such as column chromatography or solvent fractionation. The preferred degree of polymerization is at the level of disaccharide to heptasaccharide namely di N-acetyl chitobiose, tri-N acetyl chitotriose, tetra N acetyl chitotetraose, penta N acetyl chitopentaose, and hexa N-acetyl chitohexaose. (see example 1).
The chitosan oligosaccharide can be obtained by partially hydrolyzing chitosan which is obtained by subjecting chitin to a hot concentrated alkali treatment. The partial hydrolysis of chitosan is carried out by heating with an acid such as hydrochloric acid, acetic acid, or formic acid. The acid is then removed or neutralized and desalted followed by crystallization to form a powder or a method wherein chitosan is dissolved in a dilute acid and then allowed to react with enzymes such as chitosanase or D-glucosaminidase. The degree of polymerization of the chitosan oligosaccharide is then a mixture of chitobiose, chitotriose, chitotetraose, chitopentaose, chitohexaose, and chitoheptaose (see example 2).
The mixture of chitin and chitosan oligosaccharides can then be available as a water soluble powder that can be taken orally or manufactured into a chewable tablet.
The partially deacetylated chitin oligosaccharide used an ingredient of the agent of the present invention can be prepared by removing, e.g. by acid treatment, the N-acetyl groups from some of the N-acetyl glucosamine subunits of a chitin oligosaccharide.
As stated above, the agent of the present invention can function as a non-peptide bradykinin antagonist. Whether this is due to the absorption of the bradykinin molecule into the xe2x80x9cchairxe2x80x9d of the CCOS molecule (chitin means xe2x80x9cenvelopexe2x80x9d in Greek) or whether it blocks the bradykinin B2 receptor site is unclear. Blockage of the ionic charges mediated by bradykinin at the receptor sites is also postulated.
The evaluation of pain and its assessment presents several difficult problems (36, 37, 38) among which are:
pain can be an individual realization and is therefore difficult to evaluate
pain is difficult to quantify
pain is difficult to describe
pain is affected by attitudes and beliefs
A number of methods have been proposed to study pain and analgesia. These include:
visual analogue scales (a line is drawn and pain is rated at one end as xe2x80x9czero painxe2x80x9d and the other end xe2x80x9cworst imaginable painxe2x80x9d)
pain questionnaires ie the McGill Pain Questionnaire (MPQ)
numeric scales (the patient rates his pain from 0-no pain, to 5 or 10-worst imaginable pain)
pain charts
In our studies, a short form of the McGill Pain Questionnaire was used as developed by R. Melzak (1984). This modification is a hybrid form utilizing both a Visual Analogue Scale rating pain from 0 (no pain) to 5 (excruciating) as well as a pain questionnaire rating the pain from 0 (no pain) to 3 (severe) along with the following descriptions:
throbbing
shooting
stabbing
sharp
cramping
gnawing
hot-burning
aching
heavy
tender
splitting
tiring-exhausting
sickening
fearful
punishing-cruel